Cleft palate induction in hamster fetuses by glucocorticoid hormones and their synthetic analogues

The effect of prenatal administration of different doses of cortisone, corticosterone, dexamethasone, triamcinolone and prednisolone on the fetus and its palatal development was studied. All the glucocorticoids, except cortisone, produced cleft palate in the fetuses. Both the total frequency and morphologically different types of cleft palate were related to the dose of the teratogen. Triamcinolone appeared to be more potent than other glucocorticoid in inducing cleft palate. An association was noted between fetal growth inhibition, the dose of the teratogen and the frequency and type of cleft palate.

Effects of trypan blue on the development of the garden lizard, Calotes versicolor

The eggs of Calotes versicolor were exposed to different concentrations of trypan blue around the time of appearance of limb buds. The treatment resulted in malformations of limbs, hemorrhages in various locations, microphthalmia, kinky tail, and retarded development and growth of the contained embryos. The proportion of affected embryos varied significantly from clutch to clutch, perhaps due to genetic variation. All treated embryos, including those apparently unaffected, had trypan blue in the blood circulation, but not in the amniotic cavity or extraembryonic celom. Trypan blue was seen in kidney, liver, and other organs in decreasing order of frequency and concentration. On histological examination a change in the mitotic and necrotic frequency of the cells was noticed as one of the early events. The initial necrosis was close to blood vessels. The protective role of yolk sac in trypan blue-induced teratogenesis is discussed and contrary to the widely held view it is concluded that the yolk sac appears to play no such significant role in Calotes. It is suggested that trypan blue directly affects Calotes embryos, perhaps by altering cell permeability.

Effects of testosterone implants in pregnant ewes on their female offspring

Pregnant ewes were implanted with 1 g testosterone between days 30-80, 50-100, 70-120 or 90-140 of gestation. Ewes treated between days 30-80 and 50-100 showed increased aggressive behaviour and clitoral enlargement, whereas this was not seen in the day 70-120 or 90-140 groups. Although the implants released similar amounts of testosterone at all stages of gestation, plasma testosterone concentrations were lower in the day 70-120 and 90-140 groups. The increased testosterone clearance in late gestation could be a result of increased placental aromatization. Masculinization of the genital tubercle was complete in female lambs in the day 30-80 group, partial in the day 50-100 and 70-120 groups, and absent in the day 90-140 group. These results therefore suggest that the 'critical period' for masculinization of the external genitalia is between days 40 and 50 of foetal life. In contrast to this anatomical masculinization, one aspect of behavioural masculinization had a later critical period, since female lambs of 30-80, 50-100 and 70-120 day groups adopted male-like urination postures, whereas the day 90-140 offspring showed the normal female pattern.

[On aplasia of the optic nerve (author's transl)]

The occurrence of aplasia and hypoplasia of the optic nerve in man and in mammals is described. A secondary aplasia may result from additional malformations of the central nervous system. Primary aplasia may be studied in mutants of the house mouse, which show that not only the blood vessels, but also changes in time and location of the physiologic cell necrosis may be important.

Drugs in pregnancy and lactation

The hazards of exposing the human fetus to drugs have become increasingly apparent in the last 15 years, during which time drug usage has steadily increased. Even though a direct cause-and-effect relationship between certain commonly used drugs and fetal disorders or malformations has been difficult to establish, the principle of avoidance of all but essential medications in pregnancy and in the potentially pregnant has become increasingly important. This paper summarizes the factors determining fetal damage and lists the problems associated with some drugs frequently encountered in practice.

Long-term assessment of children exposed in utero to carbimazole

Twenty-five children aged 3 to 13 years who had been exposed in utero to carbimazole were assessed physically and psychologically to evaluate the long-term effects of the drug on growth and development. 2 children had congenital malformations but all had normal pituitary-thyroid function and appeared to have grown and developed normally.

[Effect of phenformin on fat-carbohydrate metabolism in pregnant rats]

Rats given phenphormin, an antidiabetic biguanide, from the 1st (8th) day of pregnancy displayed a fall of cholesterol, phospholipids and free fatty acids in the blood; no maldevelopment of the fetus or placenta was seen. Permissibility of prescription of biguanides during pregnancy is discussed.

Teratogenic and toxicological examination of 2,4,5-trichlorphenoxyacetic acid in developing chick embryos

Practical grade 2,4,5-trichlorophenoxyacetic acid (2,4,5-T), dissolved in dimethylsulfoxide (DMSO), was injected into the air space of fertilized chicken eggs prior to incubation. Doses of 2,4,5-T administered were 12.5, 25, 50, 75, 100, and 125 mg/kg to determine herbicide toxicity on the first day of incubation. A similar group was studied on day 5 of incubation with doses of 2,4,5-T at 50, 75, 100 and 250 mg/kg. LD50 was estimated to be 62 mg/kg on day zero and 68 mg/kg on day 5. Additionally, embryos were exposed to 2,4,5-T at 50 mg/kg on day zero of gestation and sacrificed after 48 h of incubation. Serial sections were examined for teratological and developmental anomalies. None were found.

[Morphogenesis of the chick embryo foot as studied by Janus green B-induced malformations]

Janus green was injected into the amniotic sac of 6-5-day-old chick embryos at a single dose of 8-5 or 15 mug; the dye causes respectively 55 and 82% malformations of the feet. Toe are affected by partial or total soft tissue syndactyly, hypophalangy and infrequently by hyperphalangy. Lateral toes are more severely and more frequently affected by syndactyly and hypophalangy than medium ones. Hyperphalangy is found exclusively in toes I and II and causes the formation of one excess phalanx at most. Syndactylous toes are joined by an overdeveloped digital membrane. Hypophalangic toes have a truncated (non-pointed) distal tip. Two phalanges are lacking at most. These malformations are due to two distinct phases of the Janus green action. The first one, which is early and fast, inhibits interdigital programmed cell death, causing in term the non-regression of the interdigital membranes and thus syndactyly. The second one, which is late and slow, blocks the apical growth; this leads to hypophalangy.

[Development of the breasts of the fetus. Effects of the administration of hormonal preparations during pregnancy]

The mammary glands of ten still-birth premature fetuses were studied histologically. In seven cases a combination of oestrogen-progesterone preparations were administered to the mother in early pregnancy for a duration of at least 3 months. In three cases no hormones were administered. According to our observations and the experimental work of other investigators, we may conclude that oestrogenic hormones inhibit the development of the mammary gland.

Perinatal nephropathies

The purpose of this paper is to review the development of the mammalian kidney and to assess the influence that various perinatal manipulations may have on the developmental process either morphologically or functionally. Immature kidneys in general have less functional capacity than adult kidneys and a low rate of glomerular filtration, perhaps related to renal blood flow, which appears to limit the disposition of a fluid or solute load. Tubular reabsorption is also limited leading to the urinary loss of glucose, amino acids, bicarbonate and phosphate. Although the relatively low function of the immature kidney is a normal part of development, its capacity to respond under conditions of stress may be less adequate than in adults. An additional concern is that a variety of perinatal manipulations, such as the incidental or accidental ingestion of a chemical, may lead to varying degrees of altered morphogenesis or functional development of the kidney. Chemical induced renal anomalies may be of several types, but in typical teratology experiments hydronephrosis may be the most frequent observation. The functional consequences of these renal malformations may be lethal or inconsequential or while an animal may be able to survive and develop normally in the presence of a renal malformation, it is possible that a stressful situation would unmask a functional malformation which could compromise survival. Thus, some renal abnormalities may be subtle enough to go unnoticed without experimental tests. Without such tests it is impossible to evaluate the effect of functional alterations on successful adaptation.

[Characteristics of chemical structure of analogs of the antimalarial drug chloridine (pyrimethamine), detetermining their teratogenic properties]

On an example of substituted 2,4-diaminopyrimidines containing at the 6th position hydrogen, alkyl radicals with a varying length of chains, ramified isoalkyl radicals and aromatic nuclei it is shown that the teratogenous activity is inherent only in some agents, being related to the chemical structure and conformation of the molecules. Accordingly, the principles of elective toxicity lying at the root of current chemotherapy may be extended also to teratology. From this it follows that there exists as a matter of principle the possibility of a purposeful synthesis of new medical compounds that would be devoid of teratogenous activity, but were endowed with valuable curative properties.